(1) Four Qi, also called four natures, refers to four medicinal properties of cold, cool, warm and hot. Among them, cold, cool, warm and hot are two kinds of medicinal properties with different properties, while cold and cool, mild and hot are only different in degree. Cool is inferior to cold and warm is inferior to heat, which is summarized according to the reaction and therapeutic effect of drug action and body. Any medicine that can treat febrile disease syndrome is considered to have the property of coldness. Cold drugs and cold drugs belong to yin and have the functions of clearing away heat, purging fire, cooling blood and detoxifying. Warm and hot drugs belong to yang, which have the functions of warming interior, resisting cold, helping yang and dredging collaterals. In addition, there are some drugs whose properties are between cold and warm, which are called flat, and can be applied to both cold syndrome and heat syndrome.

(2) Five flavors

It refers to five different medicinal flavors: sour, bitter, sweet, pungent and salty. Different herbs have different therapeutic effects.

① Sour taste contains organic acids and tannins. It has the functions of convergence and fixation. For example, pomegranate peel can astringent intestines and stop diarrhea.

② Bitter taste contains alkaloids and glycosides. It has the effects of clearing away heat, eliminating dampness and relieving diarrhea. For example, coptis can dry dampness and purge fire, and rhubarb can purge heat and relax bowels.

3 sweet and sugary. It has the functions of nourishing, harmonizing and prioritizing. For example, licorice can reconcile medicinal properties.

④ pungent taste contains volatile oil. It has the functions of dispersing, promoting qi circulation and promoting blood circulation. For example, Radix Aucklandiae can regulate qi, and Herba Asari can perspire, relieve exterior syndrome and relieve pain.

⑤ Salty taste contains minerals. It has the effects of softening hard mass, dispersing hard mass and diarrhea. For example, kelp and seaweed can soften and harden phlegm.

⑥ Some other drugs have mild and astringent taste. Light taste has the function of diuresis, such as poria cocos can diuresis and dehumidification. The astringent taste has the functions of astringency, antiperspirant, semen fixation and antidiarrheal, for example, terminalia chebula can astringent intestine and antidiarrheal.